Card fiber fleeces are made from an extremely wide variety of fibers. In general, such fleeces have the advantage that the short fibers are randomly distributed in the finished fleece so that the fleece has better stability in all pulling directions. There are also fleeces made of spun filaments which, once the filaments are made, the filaments are immediately laid down to make a fleece, for example, on an endless belt. The loosely laid fibers or filaments in the fleece produced by the carding machine and those of a spun fleece, however, have to be connected with each other to produce a level of strength that is satisfactory in practice. For this purpose, needling of the fleece mechanically with needles is known. With this fundamentally discontinuous and hence slow solidification process the volume of the fleece is considerably decreased however, so that such a mechanically solidified or needled fleece is useless for many applications. In addition, thin fleeces cannot be needled mechanically at all.
The addition of binding agents to the fibers is also known. For example, these agents are sprayed on in liquid form or by foam impregnation. The disadvantage of such fleece is not only the additional and necessarily expensive chemicals, whose production is somewhat detrimental to the environment, but also the poorer recyclability.
The addition to the fleeces of fibers made with lower-melting chemical fibers as well as bicomponent fibers is also known, and these additive fibers an be at least initially melted by the action of heat so that they stick to the adjacent fibers in the fleece. In this process, the expensive binding fibers and the additionally necessary energy for heating the binding fibers to the melting point is disadvantageous.
Needling the fleeces of the aforementioned type using water is also known. Water needling has the basic advantage of being continuous and hence allowing higher production rates. However, the stiff, paper-like products usually arising from water needling are disadvantageous.